Process for thinning varnish



Patented Feb. 2a, 1928. r

UNITED STATES-PATENT orrlcs.

ARTHUR L. snow, or EAST rrrrsnunen, v

nousn ELECTRIC a maxurncrunme conramr, A con'ronarron or PENNSYL-PENNSYLVANIA, ASSIGNOB T0 WESTING- PROCESS 'FOR THINNING- VARNISE.

No'Drawing. Application filed October 4, 1924. Serial No. 741,761

My invention relates to liquid coating compositions and specifically toa method of thinning enamel or varnish with solvents.

' In the manufacture of varnish, the varnish resin is cooked with anoil, such as linseed oil, and with other ingr'edients,-among which is adrier such as a manganese, cobalt or lead linoleate. When the varnish issufiiciently cooked or cured, a solvent or thinner, such as turpentlneor a mineral solvent, is added while the fusion is still hot. Many ofthe solvents now available, especially the mineral oil solvents, containsulphur or sulphur compounds. When suchsolvents are used for thinningthe'hot resin-oil mixture in. the 'manner well known to the art, themetals of the drier material that are capable of forming insolublesulphides, such as manganese or lead, are precipitated, thus forming aninsoluble precipitate. The thinned varnish produced'thereby is,consequently, clouded and is diflicult to clear, up. en, however, thevarnish or enamel is partly thinned with a sulphur freesolvent whilehot, a solvent containing sulphur can be used for the remainder of thethinning when the mixture is cool.

I have discovered a method of thinning varnish whereby solventscontaining sulphur and compounds of sulphur that are capable of reactingwith metals to form insoluble sulphides may be used without involvingthe recipitation of the insoluble compounds of t e metals.

A procedure which I have found successful is to add to the enamel about1/4 to 1/5 by volume of solvent, such as turpentine, when thetemperature ofthe varnish is about 175 C. The solvent added at thispoint must be free from sulphur or from compounds of sulphur which areable to react at the first thinning temperature with lead or manganeseto form insoluble sulphides.

The partially thinned varnish is then covered to prevent oxidation-fromthe air and is allowed to cool to room tem erature. The thinning is thencompleted y adding the remainder of the solvent which may be a lessrefined product and may contain sulphur and sulphur compounds, such 'asturpentine substitute. The enamel or varnish thinned "by this method isperfectly clear, has a brilliant appearance and doesnot contain anysulphide precipitate of the metals.

I have thus described a method of thinning varnish or enamel whereby asolvent which contains sulphur or sulphur compounds may be used in partfor thinning the fused resin and oil mixture. The varnish is partlythinned while hot with a sulphur free solvent and, when cold, thethinning is completed by adding a'less highly refined thinner thatcontains sulphur or sulphur compounds. By adding the thinner in the manner described, I am able to use an inex pensive and less highly refinedsolvent and to produce a clear first-class varnish.

While- I have specifically described one modification of a process forthinning varnish, I donot wish to be limited thereto, as I may vary themethod, as, for example, by making the first addition of thinner atanother temperature than the one. mentioned. The number of steps in theprocess or the amount of thinner added in each step of the process mayalso be varied without departing from the spirit of my invention, the

scope of which is defined in the annexed claims.

I claim as my invention:

1. The method of thinning varnish compounds which comprises adding a sulhurfree solvent to the hot varnish and t en a solvent containing sulphurwhen the mixture is cold.

2. The method of thinning hot varnish compounds which contains materialrecipitable by sulphur compounds, whic comprises adding a sulphur freesolvent, coolin and then adding a solvent containing su phur.

3. The method of thinning varnish compounds which comprises coolingthefused varnish resin compound to about 175 and adding a sulphur freesolvent, cooling and then adding a solvent containing sulphur.

4. The method of thinning varnish containing material precipitable bysulphur compounds which comprises cooling the fused varnish resincompound to 175 0., adding about 20% by volume of a sulphur-freesolvent, cooling and then adding a solvent containing reactive sulphurcompounds.

' ature and adding a thinner pounds,

-material and then cooling to a lower tempercontaining a reactivesulphur compound.

7. The method of thinning hot varnish her, 1924.

compounds containing material precipitable by sulphur compounds whichcomprises cooling the fused varnish resin compound to 17 5 (3., addingabout 20% by volume of a thinner which contains no sulphur compoundsthat are reactive toward said material and then cooling to a lowertemperature and adding a thinner containing a reactive sulphur compound.

I11 testimony whereof, I have hereunto subscribed my name this first dayof Octo- ARTHUR L. BROWN.

